[openocd.git] / src / jtag / drivers / bitbang.c

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007,2008 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
 ***************************************************************************/

/* 2014-12: Addition of the SWD protocol support is based on the initial work
 * by Paul Fertser and modifications by Jean-Christian de Rivaz. */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "bitbang.h"
#include <jtag/interface.h>
#include <jtag/commands.h>

/* YUK! - but this is currently a global.... */
extern struct jtag_interface *jtag_interface;

/**
 * Function bitbang_stableclocks
 * issues a number of clock cycles while staying in a stable state.
 * Because the TMS value required to stay in the RESET state is a 1, whereas
 * the TMS value required to stay in any of the other stable states is a 0,
 * this function checks the current stable state to decide on the value of TMS
 * to use.
 */
static void bitbang_stableclocks(int num_cycles);

static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk);

struct bitbang_interface *bitbang_interface;

/* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
 *
 * Set this to 1 and str912 reset halt will fail.
 *
 * If someone can submit a patch with an explanation it will be greatly
 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
 * clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
 * state". With hardware there is no such thing as *while* in a state. There
 * are only edges. So clk => 0 is in fact a very subtle state transition that
 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
 *
 * For "reset halt" the last thing that happens before srst is asserted
 * is that the breakpoint is set up. If DCLK is not wiggled one last
 * time before the reset, then the breakpoint is not set up and
 * "reset halt" will fail to halt.
 *
 */
#define CLOCK_IDLE() 0

/* The bitbang driver leaves the TCK 0 when in idle */
static void bitbang_end_state(tap_state_t state)
{
        if (tap_is_state_stable(state))
                tap_set_end_state(state);
        else {
                LOG_ERROR("BUG: %i is not a valid end state", state);
                exit(-1);
        }
}

static void bitbang_state_move(int skip)
{
        int i = 0, tms = 0;
        uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
        int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());

        for (i = skip; i < tms_count; i++) {
                tms = (tms_scan >> i) & 1;
                bitbang_interface->write(0, tms, 0);
                bitbang_interface->write(1, tms, 0);
        }
        bitbang_interface->write(CLOCK_IDLE(), tms, 0);

        tap_set_state(tap_get_end_state());
}

/**
 * Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
 * (or SWD) state machine.
 */
static int bitbang_execute_tms(struct jtag_command *cmd)
{
        unsigned num_bits = cmd->cmd.tms->num_bits;
        const uint8_t *bits = cmd->cmd.tms->bits;

        DEBUG_JTAG_IO("TMS: %d bits", num_bits);

        int tms = 0;
        for (unsigned i = 0; i < num_bits; i++) {
                tms = ((bits[i/8] >> (i % 8)) & 1);
                bitbang_interface->write(0, tms, 0);
                bitbang_interface->write(1, tms, 0);
        }
        bitbang_interface->write(CLOCK_IDLE(), tms, 0);

        return ERROR_OK;
}

static void bitbang_path_move(struct pathmove_command *cmd)
{
        int num_states = cmd->num_states;
        int state_count;
        int tms = 0;

        state_count = 0;
        while (num_states) {
                if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
                        tms = 0;
                else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
                        tms = 1;
                else {
                        LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition",
                                tap_state_name(tap_get_state()),
                                tap_state_name(cmd->path[state_count]));
                        exit(-1);
                }

                bitbang_interface->write(0, tms, 0);
                bitbang_interface->write(1, tms, 0);

                tap_set_state(cmd->path[state_count]);
                state_count++;
                num_states--;
        }

        bitbang_interface->write(CLOCK_IDLE(), tms, 0);

        tap_set_end_state(tap_get_state());
}

static void bitbang_runtest(int num_cycles)
{
        int i;

        tap_state_t saved_end_state = tap_get_end_state();

        /* only do a state_move when we're not already in IDLE */
        if (tap_get_state() != TAP_IDLE) {
                bitbang_end_state(TAP_IDLE);
                bitbang_state_move(0);
        }

        /* execute num_cycles */
        for (i = 0; i < num_cycles; i++) {
                bitbang_interface->write(0, 0, 0);
                bitbang_interface->write(1, 0, 0);
        }
        bitbang_interface->write(CLOCK_IDLE(), 0, 0);

        /* finish in end_state */
        bitbang_end_state(saved_end_state);
        if (tap_get_state() != tap_get_end_state())
                bitbang_state_move(0);
}

static void bitbang_stableclocks(int num_cycles)
{
        int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
        int i;

        /* send num_cycles clocks onto the cable */
        for (i = 0; i < num_cycles; i++) {
                bitbang_interface->write(1, tms, 0);
                bitbang_interface->write(0, tms, 0);
        }
}

static void bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size)
{
        tap_state_t saved_end_state = tap_get_end_state();
        int bit_cnt;

        if (!((!ir_scan &&
                        (tap_get_state() == TAP_DRSHIFT)) ||
                        (ir_scan && (tap_get_state() == TAP_IRSHIFT)))) {
                if (ir_scan)
                        bitbang_end_state(TAP_IRSHIFT);
                else
                        bitbang_end_state(TAP_DRSHIFT);

                bitbang_state_move(0);
                bitbang_end_state(saved_end_state);
        }

        for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++) {
                int val = 0;
                int tms = (bit_cnt == scan_size-1) ? 1 : 0;
                int tdi;
                int bytec = bit_cnt/8;
                int bcval = 1 << (bit_cnt % 8);

                /* if we're just reading the scan, but don't care about the output
                 * default to outputting 'low', this also makes valgrind traces more readable,
                 * as it removes the dependency on an uninitialised value
                 */
                tdi = 0;
                if ((type != SCAN_IN) && (buffer[bytec] & bcval))
                        tdi = 1;

                bitbang_interface->write(0, tms, tdi);

                if (type != SCAN_OUT)
                        val = bitbang_interface->read();

                bitbang_interface->write(1, tms, tdi);

                if (type != SCAN_OUT) {
                        if (val)
                                buffer[bytec] |= bcval;
                        else
                                buffer[bytec] &= ~bcval;
                }
        }

        if (tap_get_state() != tap_get_end_state()) {
                /* we *KNOW* the above loop transitioned out of
                 * the shift state, so we skip the first state
                 * and move directly to the end state.
                 */
                bitbang_state_move(1);
        }
}

int bitbang_execute_queue(void)
{
        struct jtag_command *cmd = jtag_command_queue;  /* currently processed command */
        int scan_size;
        enum scan_type type;
        uint8_t *buffer;
        int retval;

        if (!bitbang_interface) {
                LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
                exit(-1);
        }

        /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
         * that wasn't handled by a caller-provided error handler
         */
        retval = ERROR_OK;

        if (bitbang_interface->blink)
                bitbang_interface->blink(1);

        while (cmd) {
                switch (cmd->type) {
                        case JTAG_RESET:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("reset trst: %i srst %i",
                                cmd->cmd.reset->trst,
                                cmd->cmd.reset->srst);
#endif
                                if ((cmd->cmd.reset->trst == 1) ||
                                                (cmd->cmd.reset->srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
                                        tap_set_state(TAP_RESET);
                                bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
                                break;
                        case JTAG_RUNTEST:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("runtest %i cycles, end in %s",
                                                cmd->cmd.runtest->num_cycles,
                                                tap_state_name(cmd->cmd.runtest->end_state));
#endif
                                bitbang_end_state(cmd->cmd.runtest->end_state);
                                bitbang_runtest(cmd->cmd.runtest->num_cycles);
                                break;

                        case JTAG_STABLECLOCKS:
                                /* this is only allowed while in a stable state.  A check for a stable
                                 * state was done in jtag_add_clocks()
                                 */
                                bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
                                break;

                        case JTAG_TLR_RESET:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("statemove end in %s",
                                                tap_state_name(cmd->cmd.statemove->end_state));
#endif
                                bitbang_end_state(cmd->cmd.statemove->end_state);
                                bitbang_state_move(0);
                                break;
                        case JTAG_PATHMOVE:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("pathmove: %i states, end in %s",
                                                cmd->cmd.pathmove->num_states,
                                                tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
#endif
                                bitbang_path_move(cmd->cmd.pathmove);
                                break;
                        case JTAG_SCAN:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("%s scan end in %s",
                                                (cmd->cmd.scan->ir_scan) ? "IR" : "DR",
                                        tap_state_name(cmd->cmd.scan->end_state));
#endif
                                bitbang_end_state(cmd->cmd.scan->end_state);
                                scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
                                type = jtag_scan_type(cmd->cmd.scan);
                                bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
                                if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
                                        retval = ERROR_JTAG_QUEUE_FAILED;
                                if (buffer)
                                        free(buffer);
                                break;
                        case JTAG_SLEEP:
#ifdef _DEBUG_JTAG_IO_
                                LOG_DEBUG("sleep %" PRIi32, cmd->cmd.sleep->us);
#endif
                                jtag_sleep(cmd->cmd.sleep->us);
                                break;
                        case JTAG_TMS:
                                retval = bitbang_execute_tms(cmd);
                                break;
                        default:
                                LOG_ERROR("BUG: unknown JTAG command type encountered");
                                exit(-1);
                }
                cmd = cmd->next;
        }
        if (bitbang_interface->blink)
                bitbang_interface->blink(0);

        return retval;
}


bool swd_mode;
static int queued_retval;

static int bitbang_swd_init(void)
{
        LOG_DEBUG("bitbang_swd_init");
        swd_mode = true;
        return ERROR_OK;
}

static void bitbang_exchange(bool rnw, uint8_t buf[], unsigned int offset, unsigned int bit_cnt)
{
        LOG_DEBUG("bitbang_exchange");
        int tdi;

        for (unsigned int i = offset; i < bit_cnt + offset; i++) {
                int bytec = i/8;
                int bcval = 1 << (i % 8);
                tdi = !rnw && (buf[bytec] & bcval);

                bitbang_interface->write(0, 0, tdi);

                if (rnw && buf) {
                        if (bitbang_interface->swdio_read())
                                buf[bytec] |= bcval;
                        else
                                buf[bytec] &= ~bcval;
                }

                bitbang_interface->write(1, 0, tdi);
        }
}

int bitbang_swd_switch_seq(enum swd_special_seq seq)
{
        LOG_DEBUG("bitbang_swd_switch_seq");

        switch (seq) {
        case LINE_RESET:
                LOG_DEBUG("SWD line reset");
                bitbang_exchange(false, (uint8_t *)swd_seq_line_reset, 0, swd_seq_line_reset_len);
                break;
        case JTAG_TO_SWD:
                LOG_DEBUG("JTAG-to-SWD");
                bitbang_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
                break;
        case SWD_TO_JTAG:
                LOG_DEBUG("SWD-to-JTAG");
                bitbang_exchange(false, (uint8_t *)swd_seq_swd_to_jtag, 0, swd_seq_swd_to_jtag_len);
                break;
        default:
                LOG_ERROR("Sequence %d not supported", seq);
                return ERROR_FAIL;
        }

        return ERROR_OK;
}

void bitbang_switch_to_swd(void)
{
        LOG_DEBUG("bitbang_switch_to_swd");
        bitbang_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
}

static void swd_clear_sticky_errors(void)
{
        bitbang_swd_write_reg(swd_cmd(false,  false, DP_ABORT),
                STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
}

static void bitbang_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay_clk)
{
        LOG_DEBUG("bitbang_swd_read_reg");
        assert(cmd & SWD_CMD_RnW);

        if (queued_retval != ERROR_OK) {
                LOG_DEBUG("Skip bitbang_swd_read_reg because queued_retval=%d", queued_retval);
                return;
        }

        for (;;) {
                uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];

                cmd |= SWD_CMD_START | (1 << 7);
                bitbang_exchange(false, &cmd, 0, 8);

                bitbang_interface->swdio_drive(false);
                bitbang_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 32 + 1 + 1);
                bitbang_interface->swdio_drive(true);

                int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
                uint32_t data = buf_get_u32(trn_ack_data_parity_trn, 1 + 3, 32);
                int parity = buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 32, 1);

                LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
                          ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
                          cmd & SWD_CMD_APnDP ? "AP" : "DP",
                          cmd & SWD_CMD_RnW ? "read" : "write",
                          (cmd & SWD_CMD_A32) >> 1,
                          data);

                switch (ack) {
                 case SWD_ACK_OK:
                        if (parity != parity_u32(data)) {
                                LOG_DEBUG("Wrong parity detected");
                                queued_retval = ERROR_FAIL;
                                return;
                        }
                        if (value)
                                *value = data;
                        if (cmd & SWD_CMD_APnDP)
                                bitbang_exchange(true, NULL, 0, ap_delay_clk);
                        return;
                 case SWD_ACK_WAIT:
                        LOG_DEBUG("SWD_ACK_WAIT");
                        swd_clear_sticky_errors();
                        break;
                 case SWD_ACK_FAULT:
                        LOG_DEBUG("SWD_ACK_FAULT");
                        queued_retval = ack;
                        return;
                 default:
                        LOG_DEBUG("No valid acknowledge: ack=%d", ack);
                        queued_retval = ack;
                        return;
                }
        }
}

static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk)
{
        LOG_DEBUG("bitbang_swd_write_reg");
        assert(!(cmd & SWD_CMD_RnW));

        if (queued_retval != ERROR_OK) {
                LOG_DEBUG("Skip bitbang_swd_write_reg because queued_retval=%d", queued_retval);
                return;
        }

        for (;;) {
                uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];
                buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32, value);
                buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1 + 32, 1, parity_u32(value));

                cmd |= SWD_CMD_START | (1 << 7);
                bitbang_exchange(false, &cmd, 0, 8);

                bitbang_interface->swdio_drive(false);
                bitbang_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 1);
                bitbang_interface->swdio_drive(true);
                bitbang_exchange(false, trn_ack_data_parity_trn, 1 + 3 + 1, 32 + 1);

                int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
                LOG_DEBUG("%s %s %s reg %X = %08"PRIx32,
                          ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
                          cmd & SWD_CMD_APnDP ? "AP" : "DP",
                          cmd & SWD_CMD_RnW ? "read" : "write",
                          (cmd & SWD_CMD_A32) >> 1,
                          buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32));

                switch (ack) {
                 case SWD_ACK_OK:
                        if (cmd & SWD_CMD_APnDP)
                                bitbang_exchange(true, NULL, 0, ap_delay_clk);
                        return;
                 case SWD_ACK_WAIT:
                        LOG_DEBUG("SWD_ACK_WAIT");
                        swd_clear_sticky_errors();
                        break;
                 case SWD_ACK_FAULT:
                        LOG_DEBUG("SWD_ACK_FAULT");
                        queued_retval = ack;
                        return;
                 default:
                        LOG_DEBUG("No valid acknowledge: ack=%d", ack);
                        queued_retval = ack;
                        return;
                }
        }
}

static int bitbang_swd_run_queue(void)
{
        LOG_DEBUG("bitbang_swd_run_queue");
        /* A transaction must be followed by another transaction or at least 8 idle cycles to
         * ensure that data is clocked through the AP. */
        bitbang_exchange(true, NULL, 0, 8);

        int retval = queued_retval;
        queued_retval = ERROR_OK;
        LOG_DEBUG("SWD queue return value: %02x", retval);
        return retval;
}

const struct swd_driver bitbang_swd = {
        .init = bitbang_swd_init,
        .switch_seq = bitbang_swd_switch_seq,
        .read_reg = bitbang_swd_read_reg,
        .write_reg = bitbang_swd_write_reg,
        .run = bitbang_swd_run_queue,
};